JP2013124334A - Coloring composition, and image display structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coloring composition in which a pyridone-based methine dye is contained in a good melted state and which is suitable for image displays (in particular, image displays in display devices operated by the principles of the electrowetting method or electrophoresis method).SOLUTION: The coloring composition is represented by general formula (1), and includes: a pyridone-based methine dye whose solubility in n-hexane at 25°C and 0.1 MPa is 1 mass% or more; and a nonpolar solvent. In the general formula, Rand Rare an alkyl group, an alkoxy group, an aryl group, -COORor -CONRR; Ris an alkyl group, an alkoxy group, an aryl group, a cyano group, -COOR, or -CONRR; Ar is an aromatic ring or a saturated heterocycle; Rand Rare H, an alkyl group or an aryl group; Rand Rare H, an alkyl group; and n=0, 1, or 2, provided that at least one of R-Rand Ar has a 6-30C alkyl group, and R-Rand Ar have no dissociable group.

Description

  The present invention relates to a coloring composition containing a pyridone-based methine dye and an image display structure.

  In recent years, many organic dyes have been used in display materials, optical recording media, ink jet materials and the like. When a dye is used in a coating process or an ink jet process, in order to increase coloring efficiency, in addition to having a high molar extinction coefficient, it is required to have high solubility in a solvent.

  As a new image display technique, recently, a display (EWD) using an electrowetting method has attracted attention (see, for example, Non-Patent Document 1). In this display, a plurality of pixels filled with two phases of a hydrophilic medium and an oil-based coloring ink are arranged on a substrate, and the hydrophilic medium / oil-based coloring is applied by ON / OFF (OFF) of voltage application for each pixel. This is an image display system in which the affinity of the ink interface is controlled and the oil-based colored ink is developed / deformed on the substrate. A dye used for such an electrowetting display is required to have high solubility in a hydrocarbon solvent.

  Many pigments are known, and among them, pyridone-based methine pigments have been widely used for various purposes. For example, methine dyes including the following compounds D-01 and D-02 are known as dyes used for thermal transfer materials (see, for example, Patent Document 1).

JP-A-9-506918

Nature (London), 425, 383 (2003)

  However, the methine dyes conventionally proposed as described above cannot sufficiently secure solubility in nonpolar solvents, particularly solubility in hydrocarbon solvents such as decane and hexane. Therefore, for example, when applying to image display using the principle of electrowetting method or electrophoresis method, further improvement has been demanded, such as hindering image display switching (optical shutter).

  In the present invention, pyridone-based methine dyes are well dissolved and contained, and image display (particularly, image display on a display device operating on the principle of electrowetting method or electrophoresis method (for example, on / off at the time of image display). It is an object to provide a coloring composition and an image display structure suitable for the property (light shutter characteristics))), and to achieve the object.

Specific means for achieving the above object are as follows.
<1> A colored composition represented by the following general formula (1), comprising a pyridone-based methine dye having a solubility in n-hexane of 1% by mass or more at 25 ° C. and 0.1 MPa, and a nonpolar solvent. .

In the general formula (1), R ¹ and R ³ each independently represent a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, —COOR ¹¹ , or —CONR ¹¹ R ¹² , and R ² represents an alkyl group , An alkoxy group, an aryl group, a cyano group, —COOR ¹¹ , or —CONR ¹¹ R ¹² , and Ar represents an aromatic ring or a saturated heterocyclic ring. R ¹¹ and R ¹² each independently represent a hydrogen atom, an alkyl group, or an aryl group, and may be bonded to each other to form a 5-membered ring, a 6-membered ring, or a 7-membered ring. R ⁴ and R ⁵ each independently represent a hydrogen atom or an alkyl group, and adjacent R ⁴ and R ⁵ may be bonded to each other to form a ring structure. n is 0, 1, or 2. At least one of R ^{1 to} R ⁵ and Ar has an alkyl group having 6 to 30 carbon atoms, and none of R ^{1 to} R ⁵ and Ar has a dissociable group.

<2> The colored composition according to <1>, wherein Ar has at least one alkylamino group as a substituent.
<3> The colored composition according to <2>, wherein the alkyl moiety of the alkylamino group has 6 to 30 carbon atoms.
<4> At least one of R ¹ and R ³ is the colored composition according to any one of <1> to <3>, which represents an alkyl group having 6 to 30 carbon atoms.
<5> The colored composition according to any one of <1> to <4>, wherein a relative dielectric constant of the pyridone-based methine dye is 10 m or less.
<6> The colored composition according to any one of <1> to <5>, wherein a viscosity at 20 ° C. (preferably 0.01 mPa · s or more) is 10 mPa · s or less.
<7> The colored composition according to any one of <1> to <6>, which is used for an image display material of a display device that operates according to a principle of an electrowetting method or an electrophoresis method.

  <8> An oil formed using the coloring composition according to any one of <1> to <7> above, wherein the surface is disposed in contact with the hydrophobic polymer layer having a hydrophobic surface and the surface. An image display structure having a layer and a hydrophilic liquid layer disposed in contact with the oil layer.

  According to the present invention, pyridone-based methine dyes are well dissolved and contained, and image display (particularly, image display on a display device that operates on the principle of electrowetting or electrophoresis (for example, on-display at the time of image display). / Coloring composition and image display structure suitable for off-off characteristics (light shutter characteristics))).

It is a schematic sectional drawing which shows the structural example of the display apparatus which operate | moves on the principle of the electrowetting method.

  Hereinafter, the coloring composition of the present invention and the image display structure using the same will be described in detail.

<Coloring composition>
The colored composition of the present invention is represented by the following general formula (1), a pyridone methine dye having a solubility in n-hexane of 1% by mass or more at 25 ° C. and 0.1 MPa, a nonpolar solvent, It is comprised using. Moreover, the coloring composition of this invention may be comprised using other components, such as additives, such as pigment | dyes other than a pyridone-type methine pigment | dye, polar solvents, and an ultraviolet absorber, as needed.

Pyridone-based methine dyes have been widely known for various uses. However, conventional pyridone-based methine dyes have low solubility in nonpolar solvents and are used as colorants for liquid compositions composed of nonpolar solvents. Has not been used in general.
In the present invention, by using a pyridone-based methine dye having a specific structure having an alkyl group having 6 or more carbon atoms and having no dissociable group as a colorant of a coloring composition composed of a nonpolar solvent, Good solubility that does not easily cause precipitation is maintained, and image display (particularly, image display on a display device that operates on the principle of electrowetting or electrophoresis) is improved. In particular, it is excellent in on / off property (optical shutter characteristics) when displaying an image, and it is possible to display an image with a clear and good hue.

-Pyridone methine dyes-
The coloring composition of the present invention contains at least one pyridone-based methine dye represented by the following general formula (1) and having a solubility in n-hexane of 1% by mass or more at 25 ° C. and 0.1 MPa. Since this dye is excellent in solubility in a nonpolar solvent, it is suitable as a dye used for a display or the like, in particular, a display device (for example, a display) operated by the principle of the electrowetting method or the electrophoresis method.

In the general formula (1), R ¹ and R ³ each independently represent a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, —COOR ¹¹ , or —CONR ¹¹ R ¹² , and R ² represents an alkyl group , An alkoxy group, an aryl group, a cyano group, —COOR ¹¹ , or —CONR ¹¹ R ¹² , and Ar represents an aromatic ring or a saturated heterocyclic ring. R ¹¹ and R ¹² each independently represent a hydrogen atom, an alkyl group, or an aryl group, and may be bonded to each other to form a 5-membered ring, a 6-membered ring, or a 7-membered ring. R ⁴ and R ⁵ each independently represent a hydrogen atom or an alkyl group, and adjacent R ⁴ and R ⁵ may be bonded to each other to form a ring structure. n is 0, 1, or 2.
The pyridone-based methine dye has at least one linear or branched alkyl group having 6 to 30 carbon atoms and a relatively large number of carbon atoms in the molecule, and has no dissociable group. Therefore, the said pigment | dye is excellent in the solubility with respect to a nonpolar solvent.

The pyridone-based methine dye represented by the general formula (1) has a solubility in n-hexane of 1% by mass or more at 25 ° C. and 0.1 MPa, and is soluble in a nonpolar solvent, particularly a hydrocarbon solvent. It has excellent solubility. The solubility of 1% by mass or more means that, as an image display material, for example, a display member (for example, an image display structure described later) for producing a display that operates by the principle of electrowetting method or electrophoresis method. Indicates that it can be applied.
Hereinafter, the “solubility in n-hexane at 25 ° C. and 0.1 MPa” of the dye is also simply referred to as “solubility”.
A display member for producing a display that operates on the principle of electrowetting method or a display that operates on an electrophoresis method using the pyridone-based methine dye of the present invention [for example, an image display structure (eg, pixel on / off state ( When it is applied to a display member such as an optical shutter for switching image display / non-display) or a color display layer (color filter) of a display device operated by electrophoresis, the solubility is 3% by mass. Preferably, it is preferably 5% by mass or more. The higher the solubility, the better, but it is usually about 80% by mass or less.

Hereinafter, the pyridone methine dye represented by the general formula (1) will be described in detail.
The pyridone-based methine dye represented by the general formula (1) has a dissociable group (not including an NH group) such as —SO ₃ H, —PO ₃ H ₂ , —CO ₂ H, and —OH in the molecule. A non-polar dye and exhibits good solubility in non-polar solvents. Since the pyridone-based methine dye in the present invention has a linear or branched alkyl group having 6 to 30 carbon atoms in its molecule, it is excellent in solubility in a nonpolar solvent. Due to such structural features, the pyridone-based methine dye represented by the general formula (1) has an SP value (solubility parameter) close to that of a nonpolar solvent. It is estimated that the sex has improved. Since the SP value of D-01 and D-02 is different from the SP value of the solvent, it is considered that the solubility is low.
The alkyl group that the pyridone-based methine dye has in the molecule is preferably a linear or branched alkyl group having 6 to 30 carbon atoms, and more preferably 7 to 20 carbon atoms, for the same reason as described above.

In the general formula (1), R ¹ and R ³ each independently represent a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, —COOR ¹¹ , or —CONR ¹¹ R ¹² . R ¹ , R ³ , and R ¹¹ and R ¹² contained therein do not contain a dissociable group.

The alkyl group represented by R ¹ and R ³ may be unsubstituted or substituted, and is preferably an alkyl group having 1 to 30 carbon atoms. Examples of alkyl groups include methyl, ethyl, normal butyl, tertiary butyl, isopropyl, 1-methylcyclopropyl, pentyl, 3-heptyl, hexyl, octyl, and 2-ethylhexyl. And 2-methylhexyl group, normal nonyl group, normal undecyl group, chloromethyl group, trifluoromethyl group, ethoxycarbonylmethyl group, perfluoroalkyl group (for example, perfluoromethyl group) and the like are preferable. Especially, a C6-C30 alkyl group is more preferable, More preferably, it is a C7-C20 alkyl group, Especially preferably, they are a hexyl group, an octyl group, 2-ethylhexyl group, etc.

The alkoxy group represented by R ¹ and R ³ may be unsubstituted or may have a substituent, and is preferably an alkoxy group having 1 to 20 carbon atoms. Examples of alkoxy groups include methoxy, ethoxy, normal butoxy, tertiary butoxy, hexyloxy, 3-heptyloxy, normalnonyloxy, normal undecyloxy, chloromethyloxy, trifluoro Preferable examples include methoxy group, ethoxycarbonylmethoxy group, perfluoroalkyloxy group (for example, perfluoromethoxy group) and the like. Among these, an alkoxy group having 1 to 15 carbon atoms is more preferable, and a methoxy group and an ethoxy group are particularly preferable.

The aryl group represented by R ¹ and R ³ may be unsubstituted or substituted, and is preferably an aryl group having 6 to 20 carbon atoms. Examples of the aryl group include a phenyl group, 4-methoxyphenyl group, octyloxyphenyl group, octylphenyl group, 2,6-dimethylphenyl group, hexyloxyphenyl group, 4-dibutylaminophenyl group, 4- (2- Preferable examples include an ethylhexanoylaminophenyl group, 4-hexylphenyl group, etc. Among them, an aryl group having 6 to 16 carbon atoms is more preferable, and a phenyl group is particularly preferable.

R ² represents an alkyl group, an alkoxy group, an aryl group, a cyano group, —COOR ¹¹ , or —CONR ¹¹ R ¹² . R ² and R ¹¹ and R ¹² contained therein do not contain a dissociable group.
The alkyl group, alkoxy group, and aryl group represented by R ² have the same meanings as the alkyl group, alkoxy group, and aryl group represented by R ¹ and R ³ , respectively. Of these, a cyano group and —COOR ¹¹ are preferred embodiments.

In R ¹ '-COOR ¹¹ "represented by to R ³ and the" ^-CONR 11 ^{R 12', R 11} and ^{R 12} each independently represent a hydrogen atom, an alkyl group, or aryl ^{group, R 11} and R ¹² may be bonded to each other to form a 5-membered ring, a 6-membered ring, or a 7-membered ring. However, the group represented by R ¹¹ and R ¹² does not include a dissociable group.

The alkyl group represented by R ¹¹ and R ¹² may be unsubstituted or may have a substituent, and is preferably an alkyl group having 1 to 30 carbon atoms. Examples of alkyl groups include methyl, ethyl, propyl, butyl, ethoxycarbonylmethyl, normal octyl, 2-ethylhexyl, 2-methylhexyl, dodecyl, cyclohexyl, cyanoethyl, 2, Preferable examples include 2,3,3-tetrafluoropropyl group, chloroethyl group, acetoxyethyl group, and dimethylaminomethyl group. Among these, an alkyl group having 6 to 20 carbon atoms is more preferable, an alkyl group having 6 to 15 carbon atoms is further preferable, and a methyl group and an ethyl group are particularly preferable.

The aryl group represented by R ¹¹ and R ¹² may be unsubstituted or may have a substituent, and is preferably an aryl group having 6 to 12 carbon atoms. Examples of aryl groups include phenyl, 4-methylphenyl, 4-ethylphenyl, 4-t-butylphenyl, 4-methoxyphenyl, 4- (2-ethylhexyloxy) phenyl, 4-dodecyl. An oxyphenyl group is preferred. Among them, an aryl group having 6 to 10 carbon atoms is more preferable, and a phenyl group is particularly preferable.

The 5-membered ring, 6-membered ring, and 7-membered ring formed by combining R ¹¹ and R ¹² with each other are 5-, 6-, or 7-membered nitrogen-containing heterocycles containing a nitrogen atom. As the nitrogen-containing heterocycle, for example, pyrrolidine ring, piperidine ring, morpholine ring, piperazine ring, hexamethyleneimine ring and the like are preferable.
These 5-membered ring, 6-membered ring, and 7-membered ring may further have a substituent.

R ⁴ and R ⁵ each independently represent a hydrogen atom or an alkyl group, and adjacent R ⁴ and R ⁵ may be bonded to each other to form a ring structure. However, the groups represented by R ⁴ and R ⁵ do not include a dissociable group.

The alkyl group represented by R ⁴ and R ⁵ may be unsubstituted or substituted, and is preferably an alkyl group having 1 to 20 carbon atoms. Examples of alkyl groups include methyl, ethyl, normal butyl, tertiary butyl, 1-methylcyclopropyl, 3-heptyl, hexyl, 2-ethylhexyl, normal nonyl, and normal undecyl. Preferred examples include chloromethyl group, trifluoromethyl group, ethoxycarbonylmethyl group, perfluoroalkyl group (for example, perfluoromethyl group) and the like. Among these, an alkyl group having 1 to 10 carbon atoms is more preferable, and a methyl group, an ethyl group, and a tertiary butyl group are particularly preferable.

R ² and R ³ , R ⁴ and R ⁵ may be bonded to each other to form an aromatic ring. Furthermore, the formed aromatic ring may have a substituent.

When each group represented by R ^{2 to} R ⁵ has a substituent, examples of the substituent include a halogen atom, an alkyl group, an aryl group, and an alkoxy group.

Ar represents an aromatic ring or a saturated heterocyclic ring not containing a dissociable group.
The aromatic ring or saturated heterocyclic ring represented by Ar is preferably a 5-membered or 6-membered ring, such as a benzene ring, naphthalene ring, pyrrole ring, indole ring, pyridine ring, quinoline ring, pyrazine ring, quinoxaline ring, Preferable examples include aromatic rings such as a thiophene ring, thiazole ring, thiazoline ring, oxazole ring, oxazoline ring, imidazole ring and imidazoline ring, and saturated heterocyclic rings such as pyrrolidine ring, tetrahydrofuran and tetrahydrothiophene. Among these, as Ar, a benzene ring, a pyrrole ring, a furan ring, a thiophene ring, and a thiazole ring are more preferable.

The aromatic ring and saturated heterocyclic ring represented by Ar may be unsubstituted or substituted. When Ar is substituted, the substituent can be appropriately selected from substituents other than the dissociable group, and specific examples include an alkyl group, an alkoxy group, an aryl group, and a substituted amino group.
The alkyl group, alkoxy group, and aryl group have the same meanings as the alkyl group, alkoxy group, and aryl group in R ¹ and R ³ , respectively, and preferred embodiments thereof are also the same.
The substituted amino group is preferably an alkylamino group, and more preferably an alkylamino group having 6 to 30 carbon atoms (preferably 7 to 20 carbon atoms) in the alkyl moiety.
Among them, the substituent when Ar is substituted is preferably an alkyl group, an alkylamino group having 6 to 30 carbon atoms (preferably 7 to 20 carbon atoms), or an alkoxy group.

  n is 0, 1, or 2. Among these, n is preferably 0 or 1.

  Among them, the pyridone-based methine dye represented by the general formula (1) is preferably a compound represented by the following general formula (2) from the viewpoint of superior solubility in a nonpolar solvent.

In the general formula (2), R ¹ and R ³ each independently represents an alkyl group, an alkoxy group, an aryl group, —COOR ¹¹ , or —CONR ¹¹ R ¹² , and R ² represents an alkyl group or an alkoxy group. , An aryl group, a cyano group, —COOR ¹¹ , or —CONR ¹¹ R ¹² , and Ar represents an aromatic ring or a saturated heterocyclic ring. R ¹¹ and R ¹² each independently represent a hydrogen atom, an alkyl group, or an aryl group, and may be bonded to each other to form a 5-membered ring, a 6-membered ring, or a 7-membered ring. R ⁴ and R ⁵ each independently represent a hydrogen atom or an alkyl group, and adjacent R ⁴ and R ⁵ may be bonded to each other to form a ring structure. R ⁷ and R ⁸ each independently represents an alkyl group. n is 0, 1, or 2. In general formula (2), at least one of R ^{1 to} R ⁵ , R ^{7 to} R ^8, and Ar is a linear or branched alkyl group having 6 to 30 carbon atoms and having a relatively large number of carbon atoms (preferably At least one alkyl group having 7 to 20 carbon atoms) and no dissociable group.
Incidentally, ^R 1 ^{to R} 5, Ar, and n in the general formula (2) has the general formula (1) have the same meanings as ^R 1 ^{to R} 5, Ar, and n in, preferred embodiment is also the same.

The alkyl group represented by R ⁷ and R ⁸ is preferably an alkyl group having 6 to 30 carbon atoms in the alkyl moiety, and more preferably an alkyl group having 7 to 20 carbon atoms in the alkyl moiety. Specific examples of the alkyl group include heptyl group, octyl group, hexyl group, 2-ethylhexyl group, 2-methylhexyl group, nonyl group, decyl group, and undecyl group.

In the general formula (2), from the viewpoint of showing better solubility in a nonpolar solvent, among the structure of the general formula (2), R ¹ and R ³ are an alkyl group or an aryl group, and R ² Is a cyano group or COOR ¹¹ (R ¹¹ : alkyl group), R ⁴ and R ⁵ are hydrogen atoms or alkyl groups, and R ⁷ and R ⁸ are preferably alkyl groups. Further, in the structure of the general formula (2), R ¹ and R ³ are an alkyl group or an aryl group, R ² is a cyano group or COOR ¹¹ (R ¹¹ : an alkyl group), and R ⁴ and R ⁵ Is a hydrogen atom, and one or both of R ⁷ and R ⁸ is preferably an alkyl group having 6 to 30 carbon atoms (preferably 7 to 20 carbon atoms).

Hereinafter, specific examples of the pyridone methine dyes represented by the general formula (1) or (2) will be shown. The present invention is not limited by these specific examples.
In the specific examples shown below, “Ph” represents a phenyl group, “Me” represents a methyl group, “Et” represents an ethyl group, “Pr” represents a propyl group, and “Bu” represents a butyl group. .

The ET1 represents the following structure.

The ET2 represents the following structure.

  Synthesis of pyridone-based methine dyes having an alkyl group having 6 to 30 carbon atoms in the molecule is disclosed in Japanese Patent Nos. 2707371, 5-45789, 2009-263517, and 3-72340. It can carry out by the well-known method described in these.

The coloring composition of the present invention may be an embodiment containing only one type of pyridone-based methine dye, or an embodiment containing two or more types, and in the case of containing two or more types of azo-based dyes, the ratio of the dye is also arbitrary. It is.
The content of the pyridone-based methine dye represented by the general formula (1) in the coloring composition is not particularly limited, and can be prepared at any concentration depending on the purpose. The content of the pyridone-based methine dye is preferably 10% by mass or more with respect to the total mass of the composition from the viewpoint of hue, and more preferably contained at a high concentration from the viewpoint of hue and color density. Specifically, it is preferably 15% by mass or more, more preferably 20% by mass or more, and particularly preferably 25% by mass or more. Further, the upper limit of the content of the pyridone-based methine dye is preferably 70%, more preferably 50%, in that the viscosity of the composition becomes low.
When the content is in the above-mentioned range, the display device that operates based on the principle of electrowetting method or electrophoresis method, particularly an image display material responsible for the display (layer for switching on / off state of pixels (light shutter layer)) In addition, when applied to the production of a display portion such as a color display layer (color filter) of a display device that operates by electrophoresis, a higher contrast ratio can be obtained, and response speed and voltage can be further reduced. .

  When pyridone-based methine dyes are used as purple or magenta dyes for display displays that operate on the principle of the electrowetting method, the concentration is usually 0.2% by mass or more, and the required εC value (ε is the coloring composition) Depending on the extinction coefficient of the product).

  In addition, the colored composition of the present invention may be configured using only the pyridone methine dye represented by the general formula (1). May also be included. For example, the pyridone methine dye in the present invention and a red or blue dye having a structure different from that of the pyridone methine dye may be mixed to form a black composition.

-Other dyes-
Other dyes that may be contained in the colored composition of the present invention can be arbitrarily selected from dyes having solubility and dispersibility in a nonpolar solvent as long as the effects of the present invention are not impaired. .

  For example, when the coloring composition of the present invention is used for a display using an electrowetting method, as the other dye, an arbitrary dye can be selected from those which are dissolved in a nonpolar solvent such as an aliphatic hydrocarbon solvent. Specific examples include Oil Blue N (alkylamine-substituted anthraquinone), Solvent Green, Sudan Red, Sudan Black, and the like.

-Non-polar solvent-
The coloring composition of the present invention contains at least one nonpolar solvent. The nonpolar solvent refers to a solvent having a small dielectric constant (so-called nonpolar solvent).

  The nonpolar solvent in the present invention is a solvent that dissolves the pyridone-based methine dye. For example, an aliphatic hydrocarbon solvent such as n-hexane, n-decane, dodecane, tetradecane, hexadecane (preferably having 6 carbon atoms). To 30).

  Although the coloring composition of this invention contains a nonpolar solvent, if it is a range which does not impair the effect of this invention, it may contain the other solvent which does not correspond to a nonpolar solvent.

  In this invention, 70 mass% or more is preferable with respect to the solvent whole quantity, and, as for content in the coloring composition of this invention of a nonpolar solvent, 90 mass% or more is more preferable. When the content of the nonpolar solvent is 70% by mass or more, the solubility of the pyridone-based methine dye is kept better, and the colored composition of the present invention can be used, for example, by the principle of electrowetting or electrophoresis. When applied to an operating display device, more excellent optical shutter characteristics and display contrast can be exhibited. In the present invention, a composition using only a nonpolar solvent (ratio of the nonpolar solvent in the total solvent amount is 100% by mass) is more preferable as the solvent component.

-Other components-
In addition, the coloring composition of this invention may contain various additives, such as arbitrary ultraviolet absorbers and antioxidants, as needed.
Although there is no restriction | limiting in particular in content of an additive, Usually, it is used at about 20 mass% or less with respect to the total amount of a coloring composition.

  The display which operates on the principle of the electrowetting method by dissolving the pyridone-based methine dye of the present invention and other dyes used as necessary in a nonpolar solvent such as the aliphatic hydrocarbon solvent described above. It can be a colored solution (eg ink) for the device.

The viscosity of the colored composition of the present invention is preferably 10 mPa · s or less in terms of dynamic viscosity at 20 ° C. Among these, the viscosity is preferably 0.01 mPa · s or more, and more preferably 0.01 mPa · s or more and 8 mPa · s or less. When the coloring composition has a viscosity of 10 mPa · s or less, it is suitable for use as an image display material of a display device that operates according to the principle of electrowetting or electrophoresis, and particularly operates according to the principle of electrowetting. When applied to an optical shutter at the time of image display, it is preferable in that it can be driven at a lower voltage because the response speed is faster than a composition having a large viscosity.
The dynamic viscosity is a value measured by adjusting a 10% by mass decane solution of a pigment to 20 ° C. using a viscometer (500 type, manufactured by Toki Sangyo Co., Ltd.).

The colored composition of the present invention preferably has a small relative dielectric constant, more preferably in the range of 2.0 to 10.0. Within this range, the coloring composition of the present invention is suitable for use as an image display material of a display device that operates on the principle of electrowetting or electrophoresis, and particularly an image that operates on the principle of electrowetting. When applied to an optical shutter at the time of display, it is preferable in that it can be driven at a lower voltage because the response speed is faster than a composition having a large relative dielectric constant.
The relative dielectric constant was measured by injecting the colored composition into a glass cell with an indium tin oxide (ITO) transparent electrode having a cell gap of 10 μm, and measuring the electric capacity of the obtained cell with a model 2353 LCR meter (measurement frequency) 1 kHz) at 20 ° C. and 40% RH.

<Image display structure and display device>
In the colored composition of the present invention, the pyridone-based methine dye contained in the colored composition is excellent in solubility in a non-polar solvent, particularly a hydrocarbon solvent. It is useful as an image display material used in a display device (display) that operates by an apparatus (display) or electrophoresis. Therefore, the colored composition of the present invention is suitably used for production of an image display structure responsible for image display in these display devices.

The principle of the electrowetting method is described in International Publication No. 2005-098524. This principle uses a phenomenon in which a hydrophobic oil layer disposed on a polymer having a hydrophobic surface is deformed by applying a voltage. The hydrophobic liquid (oil droplet) and the polymer solid (for example, the polymer layer) are surrounded by a hydrophilic liquid (for example, water or a hydrophilic electrolyte solution containing an electrolyte such as ethylene glycol or tetrabutylammonium salt). A display that operates on this principle uses, for example, a substance having a hydrophobic surface that is not compatible with water, for example, on a substrate far from the observation surface of the display, and a hydrophilic liquid is formed between the substrate and the electrode near the observation surface. And a voltage is applied in a state filled with colored oil droplets (hydrophobic liquid). A voltage difference is generated by the voltage applied between the hydrophilic liquid and the electrode, and as a result, a Coulomb-like interaction appears between the hydrophilic liquid and the electrode and attempts to approach each other. Accordingly, the hydrophobic liquid is deformed so as to cover only a part of the pixel bottom portion without completely covering the pixel bottom portion. The polymer layer having the hydrophobic surface preferably exhibits transparency, and the portion that is no longer covered with the hydrophobic liquid is in a transparent state. The change in the shape of the hydrophobic liquid when the maximum voltage is applied and when no voltage is applied can be perceived by the observer as an “on” or “off” state of the pixel. There are two types of displays operating on this principle: transmissive and reflective. In the case of the transmissive type, in the “on” state, the oil droplets covering the hydrophobic substrate surface move and light can be seen through the hydrophilic liquid, so that the pixel looks “transparent”, and in the “off” state, the color appears Alternatively, the appearance of black gives an optical impression. In the reflective type, the polymer solid to be used is white, and further, a reflective layer is used below the electrode. In the case of the reflective type, in the “on” state, the oil droplets covering the hydrophobic substrate surface move and the polymer solid is exposed, and the white color can be seen through the hydrophilic liquid, so the pixel is viewed as “white”. On the other hand, in the “off” state, an optical impression is generated by appearing in color or black.
As described above, the compound used for coloring the oil droplets, which is a hydrophobic liquid, is required to have good solubility in the nonpolar solvent constituting the oil droplets. The colored composition of the present invention has good solubility in a nonpolar solvent of a methine dye and is suitable for a display method using the electrowetting method.

As a specific example, a polymer layer having a hydrophobic surface, an oil layer that is disposed in contact with the surface of the polymer layer, and is formed using the colored composition of the present invention described above, and the oil layer And an image display structure provided with at least a hydrophilic liquid layer disposed in contact with the liquid crystal. As an example of a display device having such an image display structure, the electrowetting element shown in FIG. 1 may be used.
As shown in FIG. 1, the electrowetting element 50 is a cell that is disposed opposite to an incident surface 21 a on which light is incident, an exit surface 21 b on which light is emitted, and a plurality of side surfaces 21 c and 21 d. 21, an electrode 14 disposed in the cell, an insulating layer (polymer layer) 13 disposed on the electrode 14, an oil layer 12 in contact with the insulating layer 13 and filled in the cell, and an oil layer 12 And a hydrophilic liquid layer 11 filled in the cell, and a power source 25 for electrically connecting the hydrophilic liquid layer 11 and the electrode 14. In addition, this element is disposed outside the cell 21 and a switch SW26 for turning on / off the power supply 25, and a light source 27 for irradiating the cell 21 is attached.
Since the insulating layer 13 is formed using a hydrophobic material, when the switch SW26 is off, the oil layer 12 contacts the surface of the insulating layer 13, and the oil layer 12 causes the hydrophilic liquid layer 11 and the insulating layer 13 to Is isolated. On the contrary, when the switch SW26 is turned on, the electrode and the hydrophilic liquid layer 11 are charged, so that a Coulomb interaction occurs with each other, the affinity between the electrode 14 and the hydrophilic liquid layer 11 increases, and the oil layer 12 is insulated. The contact surface with the layer 13 moves in a direction that minimizes. Here, the oil layer 12 is formed using the above-described coloring composition of the present invention, and when the switch SW26 is turned off, the hue of the oil layer 12 is favorably switched, and when the switch SW26 is turned on, the transparent display is favorably switched. It is done. At this time, the hydrophilic liquid layer 11 may be colored in a desired hue such as red, green, and blue, and a two-color display based on a hue composed of an oil layer and a hydrophilic liquid layer and a hue of the hydrophilic liquid phase is possible. Is possible. In addition, a plurality of cells exhibiting a desired hue (for example, RGB three primary colors) by various combinations of hues of the hydrophilic liquid layer and the oil layer are arranged in one pixel, and a voltage is selectively supplied in units of the cells. Images can also be displayed. When the hue of the oil layer 12 is black, the light is blocked when the switch SW26 is off, and the light emitted from the light source 27 when turned on reaches the emission surface 21b and is displayed in white. Black and white display is possible.

  Electrowetting technology in displays has many advantages such as low energy consumption compared to other display technologies and quick switching of pixel display state (reduction of switching time), which is essential for video display. ing. Furthermore, the color of the pixel is ensured by the coloring material dissolved in the hydrophobic liquid, so that the pixels of the display can exhibit various colors. The colorant must be insoluble in the hydrophilic liquid. Thereby, a transmissive display based on red (R), green (G), blue (B) and black, or a reflective type based on cyan (C), magenta (M), yellow (Y) and black. A display can be realized.

  The magnitude of the Coulomb interaction between the electrode and the hydrophilic liquid is proportional to the applied voltage. Therefore, various gray scales can be expressed in the pixel according to the voltage, and a high-quality image can be generated on the display.

  In addition to displays, electrowetting can be used for optical filters, adaptive lenses, and lab-on-chip technology.

  Electrophoresis is a principle that utilizes a phenomenon in which charged particles dispersed in a solvent move by an electric field, and has the advantage of low power consumption and no viewing angle dependency.

  A display that operates based on the principle of electrophoresis is paired with a dispersion liquid (an image display structure that bears a color display function (eg, a color filter)) in which charged particles are added and dispersed in a colored solution. By arranging between a plurality of substrates and applying a voltage of about several volts between the substrates, the particles move in the liquid phase to display an image. For example, by using the colored composition of the present invention as a colored solution and microcapsulating a dispersion liquid in which charged particles are dispersed, the color solution is disposed between two paired substrates. A display configured by providing an image display structure (so-called color filter) responsible for display is conceivable. The colored composition of the present invention has good solubility in a nonpolar solvent of a pyridone-based methine dye and is suitable for a display method using the electrophoresis method.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist thereof. Unless otherwise specified, “part” is based on mass.

[Examples 1 to 6]
-1. Preparation of coloring solution
Pyridone-based methine dye (prepared in the table below, the exemplified compounds D-2, D-4, D-5, D-17, E-1, and E-5 are prepared) and n-hexane (n -Hexane) was mixed to prepare a 15% by mass n-hexane solution (colored composition) of a pyridone-based methine dye, and six types of colored solutions were prepared.

About each produced coloring solution, the solubility (mass%) of each pyridone-type methine pigment | dye with respect to a hue, absorption maximum wavelength ((lambda) _max ), a light absorbency (abs), an extinction coefficient ((epsilon)), and n-hexane was measured and evaluated. The results of measurement and evaluation are shown in Table 1 below.

-2. Measurement / Evaluation
(1) Hue Each colored solution (colored composition) was visually observed to determine its hue.

(2) Absorption maximum wavelength, absorbance, and extinction coefficient For a colored solution (colored composition), the absorption maximum wavelength (λ _max ) and absorbance were measured with a visible light absorptiometer (UV-1800PC, manufactured by Shimadzu Corporation). In addition, the extinction coefficient (ε) was calculated based on Lambert-Beer's law.

(3) Solubility in n-hexane The solubility of each pyridone-based methine dye in n-hexane, which is a nonpolar solvent, was measured as follows.
Each dye was dissolved in n-hexane heated to 50 ° C. to prepare a saturated solution, and then the obtained saturated solution was allowed to stand in an environment of 25 ° C. and 0.1 MPa for 1 hour. The deposited dye was filtered and the amount of precipitation was measured to calculate the solubility (mass%) of each dye in n-hexane at 25 ° C. and 0.1 MPa.

(4) Measurement of dynamic viscosity A 2 mass% solution of pyridone-based methine dye in hexane was prepared, and the viscosity at 20 ° C was measured using an R-type viscometer (500 type, manufactured by Toki Sangyo Co., Ltd.).

(5) Measurement of relative dielectric constant A 5 mass% solution, a 7.5 mass% solution, and a 10 mass% solution (all colored solutions) obtained by dissolving a pyridone-based methine dye in n-hexane were prepared. Each of the obtained colored solutions was poured into a glass cell with an indium tin oxide (ITO) transparent electrode having a cell gap of 10 μm. The electric capacity was measured for each of these glass cells (measurement frequency: 1 kHz). Moreover, the reference cell which inject | poured only n-hexane into the same glass cell as the above was prepared, and the electric capacity of this reference cell was also measured. The electric capacity of the obtained cell was measured at 20 ° C. and 40% RH using a model 2353 LCR meter (measurement frequency: 1 kHz) manufactured by NF Corporation.
The relative permittivity of the colored solution was determined by the above measurement, and the relative permittivity of the pyridone methine dye itself was calculated from the relative permittivity by an extrapolation method.
When the relative dielectric constant is applied to a display device that operates based on the principle of electrowetting or electrophoresis, for example, a lower relative dielectric constant is preferable in that the power consumption is reduced because it responds at a lower voltage. .

[Comparative Examples 1-2]
A colored solution (colored composition) was obtained in the same manner as in Example 1 except that the exemplified compound D-2 used as the pigment in Example 1 was replaced with the following comparative compounds D-101 and D-102, respectively. Were prepared, and the hue, absorption maximum wavelength, absorbance, extinction coefficient, and solubility of the resulting colored solution were measured and evaluated. The results of measurement and evaluation are shown in Table 1 below.

As shown in Table 1, the pyridone-based methine dye in the present invention showed higher solubility in hexane, which is a hydrocarbon solvent, than the comparative compound for comparison. The produced colored solution (colored composition) had a large extinction coefficient.
Therefore, the colored composition of the present invention is suitable for the use of a display device that operates on the principle of the electrowetting method or a display device that operates on the electrophoresis method. When applied to a display, the colored composition exhibits excellent image display. On / off properties (so-called optical shutter characteristics) can be obtained.

  Further, when the viscosity of the pyridone methine dye in the present invention was measured by the above method, it showed a low viscosity as shown in Table 2 above. Since the coloring composition of the present invention has a high dye concentration and low viscosity, for example, a display device that operates on the principle of electrowetting or electrophoresis, particularly an image display that operates on the principle of electrowetting. When applied to the optical shutter in this case, a high contrast ratio, a fast response speed, and a low voltage can be achieved. Furthermore, the relative permittivity of the pyridone-based methine dye in the present invention is a high value as shown in Table 2, and from this point, it is applicable to a display device that operates on the principle of electrowetting method or electrophoresis method. Suitable.

Example 7
Components in the following composition were mixed to prepare a black solution having a pyridone-based methine dye concentration of 16% by mass.
<Composition>
・ The following dye Y-1 ... 190mg
-Pyridone-based methine dye (Exemplary Compound D-2 described above) ... 160 mg
Pyridone methine dye (Exemplary Compound E-1 as described above) 150 mg
・ Dye C-1 below: 300mg
・ N-decane ... 1200mg

  When the dynamic viscosity was measured by the same method as in Example 1, it showed a low value of 5.5 mPa · s. For example, when applied to a display device operating on the principle of electrowetting or electrophoresis. High contrast ratio and fast response speed can be obtained.

[Examples 8 to 14]
As shown in FIG. 1, a cell in which an ITO electrode 12 and an insulating layer 13 made of a fluoropolymer (Cytop, manufactured by Asahi Glass Co., Ltd.) are sequentially arranged is prepared, and manufactured in Examples 1 to 7 in this cell. Each of the colored solution or the black solution is filled, and an aqueous sodium chloride solution or ethylene glycol (hydrophilic liquid) is filled thereon to produce an electrowetting element.
The produced electrowetting element is excellent in display on / off characteristics (so-called optical shutter characteristics) when displaying an image.

  The colored composition of the present invention is suitably used for a display device such as a display, in particular, a display device that operates on the principle of the electrowetting method and a display device that operates on the electrophoresis method.

50 ... Electrowetting element 21 ... Cell 14 ... Electrode 13 ... Insulating layer (polymer layer)
12 ... Oil layer 11 ... Hydrophilic liquid layer

Claims (8)

A coloring composition comprising a pyridone-based methine dye represented by the following general formula (1) and having a solubility in n-hexane of 1% by mass or more at 25 ° C. and 0.1 MPa, and a nonpolar solvent.

[In General Formula (1), R ¹ and R ³ each independently represent a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, —COOR ¹¹ , or —CONR ¹¹ R ¹² , and R ² represents an alkyl group. , An alkoxy group, an aryl group, a cyano group, —COOR ¹¹ , or —CONR ¹¹ R ¹² , and Ar represents an aromatic ring or a saturated heterocyclic ring. R ¹¹ and R ¹² each independently represent a hydrogen atom, an alkyl group, or an aryl group, and may be bonded to each other to form a 5-membered ring, a 6-membered ring, or a 7-membered ring. R ⁴ and R ⁵ each independently represent a hydrogen atom or an alkyl group, and adjacent R ⁴ and R ⁵ may be bonded to each other to form a ring structure. n is 0, 1, or 2. At least one of R ^{1 to} R ⁵ and Ar has an alkyl group having 6 to 30 carbon atoms, and none of R ^{1 to} R ⁵ and Ar has a dissociable group. ]   The colored composition according to claim 1, wherein Ar has at least one alkylamino group as a substituent.   The colored composition according to claim 2, wherein the alkyl moiety of the alkylamino group has 6 to 30 carbon atoms. The colored composition according to any one of claims 1 to ³ , wherein at least one of R ¹ and R ³ represents an alkyl group having 6 to 30 carbon atoms.   The coloring composition according to any one of claims 1 to 4, wherein a relative dielectric constant of the pyridone-based methine dye is 10 m or less.   The colored composition according to any one of claims 1 to 5, wherein the viscosity at 20 ° C is 10 mPa · s or less.   The coloring composition of any one of Claims 1-6 used for the image display material of the display apparatus which operate | moves by the principle of an electrowetting method or an electrophoresis method. A hydrophobic polymer layer having a hydrophobic surface;
An oil layer disposed in contact with the surface and formed using the colored composition according to any one of claims 1 to 7,
A hydrophilic liquid layer disposed in contact with the oil layer;
An image display structure.